Mycobacterium tuberculosis is the cause of tuberculosis. This disease currently afflicts 30,000,000 people in the world and causes 10,000,000 deaths annually. The objectives of this research work are to identify, purify, and characterize antigens or individual epitope-containing moieties of antigens which are restricted to and specific for M. tuberculosis and related mycobacterial species and to assess the ability of these antigens or antigenic moieties to elicit specific immunologic responses in infected subjects. Mouse hybridoma monoclonal antibodies to M. tuberculosis antigens will be developed. These monoclonal antibodies will be used to purify individual antigens by immunoabsorbent affinity chromatography. Purified antigens will be hydrolyzed using trypsin or other means and peptides and polypeptides will be isolated. The ability of these peptides to inhibit well characterized monoclonal antibodies and patient sera in enzyme-linked immunosorbent assays will be tested. The ability of peptides to elicit cellular hypersensitivity responses will be assessed by skin testing of sensitized guinea pigs and by measuring thymidine incorporation by lymphocytes from human donors. The reactivity of monoclonal antibodies reacting with individual antigens and antigenic moieties will be studied using immunoblotting of whole mycobacterial culture filtrates. These studies should allow the estimation of the species specificity of epitopes present on peptides. Studies will be performed initially with M. tuberculosis antigen 5, a well characterized cytoplasmic antigenic protein for which there is some evidence of species restriction. Subsequently these studies will be extended to other antigens of M. tuberculosis. These investigations may lead to improved reagents for skin testing and serological immunodiagnosis of tuberculosis and may provide important new reagents for the study of the immunopathogenesis of tuberculosis.